Hypergolic propellants

ABSTRACT

A method for bringing about the auto-ignition of dicyanfuroxan or dicyanofurazan by bringing these compounds in contact with hydrazine. Monomethylhydrazine, unsymmetrical dimethyl hydrazine, piperizine, piperdine or diethylamine. The resultant formulation provides an effective hypergolic bipropellant system for use in the propulsion of rockets.

mite States atet Benson et a1.

[ June 26, 1973 HYPERGOLIC PROPELLANTS [76] Inventors: Donald D. Denson, 130 B Cannonbury Court, Kettering, Ohio; Francis M. VanMeter, 650 Montclair Drive, Lexington, Ky. 40502 [22] Filed: Aug. 4, 1972 [21] Appl. No.: 277,955

[52] US. Cl 60/215, 60/211, 149/36, 149/109 [51] Int. Cl C06d 5/08 [58] Field of Search 60/211,215, 217; 149/36, 109

[56] References Cited UNITED STATES PATENTS 2,874,535 2/1959 Ayers et a1 60/215 Scott et a1 60/215 Bell 60/215 Primary Examiner-Benjamin R. Padgett Attorney-Harry A. Herbert, Jr. et a1.

[5 7 ABSTRACT 5 Claims, No Drawings BACKGROUND OF THE INVENTION This invention relates to a propellant formulation for use with rocket motors. More particularly, this invention concerns itself with an energetic bipropellant and to a method for achieving the hypergolic ignition of the bipropellant by a method which involves bringing the compounds dicyanofuroxan or dicyanofurazan into contact with a second compound which is either a hydrazine or an amine.

Liquid propellant rocket motors usually consist of a combustion chamber, exhaust nozzle, oxidant tank, fuel tank, propellant injection system and control valves. In the combustion chamber, high temperature gases are produced by a reaction between a fuel and an oxidizer. The gas so produced is expelled from the exhaust nozzle at high speed and provides the necessary thrust to propel the rocket. In a bipropellant system, the fuel component may comprise kerosene, alcohol or hydrogen which reacts upon ignition with an oxidizer component such as oxygen or nitric acid to produce the propelling gas. Some bipropellants require an igniting means such as a spark plug, glow coil or pyrotechnical igniter in order to initiate the reaction between the fuel and the oxidizer. Other bipropellant systems, however, ignite spontaneously upon contact between the fuel and oxidizer and are called hypergolic propellants.

It is most desirable that ignition takes place immediately upon the contacting of the propellant components in the combustion zone. Otherwise, an excessive quantity of the propellant will accumulate in the combustion zone before ignition occurs. This produces a dangerous condition which invites explosive destruction of the rocket motor and injury to attendant personnel. This risk may be prevented by using hypergolic propellants.

As a consequence of the above, considerable interest has been generated in an attempt to provide an efficient means for causing the hypergolic or spontaneous ignition of a bipropellant system. In accordance with these attempts, it has been found that dicyanofuroxan and dicyanofurazan provide hypergolic combinations with certain hydrazines and amines. These hypergolic combinations provide spontaneous autoignition at room temperature and atmospheric pressure as well as at elevated temperatures and under either an inert or oxygen containing environment.

SUMMARY OF THE INVENTION In accordance with the broad concept of this invention, it has been found that dicyanofuoroxan and dicyanofurazan form hypergolic combinations with hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine, piperidine, piperazine and diethylamine. These hypergolic combinations provide efficient bipropellant systems for rocket motors. They also provide a means for igniting dicyanofuroxan, dicyanfurazan, hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine, and mixtures of three hydrazines as monopropellants. Combinations of dicyanofurazan with the hydrazines and amines referred to above are also potential high explosives.

Accordingly, the primary object of this invention is to provide an improved method for operating liquid propellant reaction motors.

Another object of the invention is to provide an improved method for reducing the ignition delay of a hypergolic propellant system in a rocket motor.

Another object of the invention is to provide propellant compositions which render either dicyanofuroxan or dicyanofurazen reaction systems hypergolic.

A further object of this invention is to provide a hypergolic bipropellant formulation.

Still further objects and advantages of the present invention will become more readily apparent upon consideration of the following detailed description thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT In general, the above-defined objects are accomplished by a novel method that brings either dicyanofuroxan or dicyanofurazan in contact with either a hydrazine selected from the group consisting of hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine and mixtures thereof or an amine selected from the group consisting of piperidine, piperazine and diethylamine.

The combination of either dicyanofuroxan or dicyanofurazan with the hydrazine and amine compounds referred to above (including mixtures of these compounds and diluted solutions of these compounds) causes auto-ignition, spontaneous or time-delayed hypergolycity or detonation at room temperature and atmospheric pressure as well as at elevated temperatures and pressures under either an inert or an oxygen containing environment.

In order to effect ignition at room temperature and atmospheric pressure or elevated temperature and atmospheric pressure, a sample of dicyanofuroxan or dicyanofurazan is placed in an aluminum weighing pan or other suitable container. A few drops of any of the hydrazine or amine compounds referred to above are added. The atmospheric pressure and elevated temperature experiments may be accomplished by heating the mixture on a hot plate or oil bath. Inert atmosphere experiments may be accomplished by mixing and heating in a glove bag charged with nitrogen.

Experiments designed to test detonation or ignition at elevated pressures and temperatures, or a combination of temperatures, pressures and atmospheres, are accomplished byemploying a somewhat more sophisticated apparatus. A 500mg sample of dicyanofuroxan is placed in a stainless steel tube or heavy wall glass capillary tube (25-40 mg of dicyanofuroxan is used in the glass system) which is sealed at one end. The other reactant is introduced under pressure by means of a remote-control valve. If heating is desired, an oil or sand bath is employed. In cases where ignition or detonation occurs only at elevated temperatures and pressures, the dicyanofuroxan and the hydrazine or amine material can be mixed prior to initiation of heating and pressurization. It should be noted, however, that cantion is required because at 750 psi (nitrogen), 35C, volume 8 ml, a mixture of 2.5 g and dicyanofuroxan and 0.5 ml of hydrazine detonates on mixing with a force sufficient to cut a stainless steel tube in half.

The high temperature and pressure testing apparatus of the invention was designed to approximate rocket motor conditions. Also, the hypergolic combinations may be tired in a conventional rocket motor by injecting the two components separately but simultaneously into the combustion chamber of the rocket motor.

In order that those skilled in the art may further understand how the present invention is carried into effect, the following examples are presented. Although the examples depict specific embodiments of the invention, it should be understood that the examples are illustrative only and should not be construed as limiting the invention in any way.

Example 1 100 mg of dicyanofuroxan was placed in an aluminum weighing pan and one drop of hydrazine was added. Hypergolic reaction was observed.

Example 2 The same hypergolic reaction as in example 1 was observed when an equal mixture of hydrazine and unsymmetrical dimethylhydrazine was employed in lieu of the hydrazine component of example 1.

Example 3 The same results as perceived in example 1 occurred when 100 mg of dicyanofuroxan were ignited by a drop of hydrazine within an inert atmosphere of nitrogen.

Example 4 250 mg of dicyanofuroxan were placed in a stainless steel tube under 500 psi of nitrogen. Hydrazine was placed behind a check valve at 850 psi. The valve was opened resulting in an instantaneous explosion. The above example was repeated several times under pressures of nitrogen gas ranging from between 13 psi to 1000 psi with the same explosive results.

As can be seen from the above, dicyanfuroxan ignites spontaneously on contact with hydrazine. It also ignites spontaneously on contact with monomethylhydrazine, unsymmetrical dimethylhydrazine and mixtures of all three in proportions. Dicyanfuroxan also ignites spontaneously on contact with piperidine, and when heated to just above its melting point (40C) it ignites spontaneously on contact with piperazine. Dicyanofurazan also ignites spontaneously on contact with the above hydrazines and amines.

The method of this invention and the resultant propellant formulations provide an energetic hypergolic bipropellant system for use in the propulsion of rockets and in high power laser applications. The invention is useful for igniting hydrazines in monopropellant propulsion systems and for igniting dicyanofuroxan and dicyanofurazan in high power laser systems. The formulations are also useful as two-component high explosives at high pressures.

While the invention has been described with particularity in reference to specific embodiments thereof, it is to be understood that the disclosure of the present invention is for the purpose of illustration only and it is not intended to limit the invention in any way, the scope of which is defined by the appended claims.

We claim:

1. A method for effecting the spontaneous ignition of a compound selected from the group consisting of dicyanofuroxan and dicyanofurazan which comprises bringing said compound in contact with a second compound selected from the group consisting of hydrazine, monomethylhydrazine, unsymmetrical dimethylhydrazine, piperadine, piperazine, diethylamine and mixtures thereof.

2. A method in accordance with claim 1 wherein said contact is brought about within an inert atmosphere.

3. A method in accordance with claim 2 wherein said contact is brought about within an inert atmosphere of nitrogen at pressures within the range of 13 and 1000 psi.

4. A method in accordance with claim 1 wherein dicyanofuroxan is contacted with hydrazine.

5. A method in accordance with claim 1 wherein dicyanofuroxan is contacted with an equi-proportional mixture of hydrazine and unsymmetrical dimethylhydrazine. 

2. A method in accordance with claim 1 wherein said contact is brought about within an inert atmosphere.
 3. A method in accordance with claim 2 wherein said contact is brought about within an inert atmosphere of nitrogen at pressures within the range of 13 and 1000 psi.
 4. A method in accordance with claim 1 wherein dicyanofuroxan is contacted with hydrazine.
 5. A method in accordance with claim 1 wherein dicyanofuroxan is contacted with an equi-proportional mixture of hydrazine and unsymmetrical dimethylhydrazine. 